Help !!!! on Samsung GT-S5233W

Hello friends,
JUST bought the GT -S5233W now facing issue with dialing confernce no.s with particant code. "could not dial" the "particant code" to join the confernce as the key pad is not activated. after dialing the actual "confernce no.s" thease are international toll free no.s.
any" help" on the same is most welcome as i am just picced of with the same.
thanks for all your help and support in advance.